Many automobiles include two rows of seats: a front row seat or seats and a rear row seat or seats. Especially for two door vehicles, the front seats often have mechanisms that allow the front row of seats to recline or move forward a relatively large amount to allow easy entry or access to the rear row of seats. Forward reclining of seats is commonly referred to as dumping. Conventional mechanisms include latches that permit the unlatching of the front row seat back recliner to pivot in a forward direction. After the rear row occupant is seated, the seat can be moved rearward back to its normal position. Some vehicle seats are also equipped with recliners that adjust the angle of the front seat back relative to the seat bottom for occupant comfort. To provide easy rear seat entry, these conventional seats include an additional mechanical latch that disengages the linkages to permit the seat back to be manually pivoted forward by a relatively large amount.
These seat latches are designed to sustain large forces during normal use, e.g. the weight and movement of the occupant, and even larger forces during an impact. Under vehicle impact conditions, large impact forces may be delivered to the seat back in both a rearward or frontal impact. In a rearward impact, the occupant is forced against the seat back, and the seat may therefore experience a large energy pulse. Similarly, in a forward impact and in vehicle seats which incorporate a belt restraint system directly connected to the seat back, the occupant will engage the restraint system, and therefore cause a relatively large energy pulse or force acting on the seat back via the restraint system. A latching device can be adapted to be attached between a seat back, a seat bottom, and/or a seat track.
In the past, more than one latching mechanism was used on seats to control reclining and dumping and to provide sufficient support against large forces. If a single mechanism was used, it was typically bulky. These bulky devices were also relatively heavy and expensive. Additionally, these bulky devices made reclining or dumping the seat more difficult since larger spring forces were required to move the mechanisms. Also, these mechanisms only managed the forces applied to the seat and did not assist with other undesirable seatback motion.
Strong seatback supports commonly have the additional drawback what is commonly known as xe2x80x9cchuckingxe2x80x9d motion. This is the undesirable differential movement of the seatback relative to the seat bottom. Generally, the seat recliner is pivotably connected to the seatback and seat frame at a pivot point and the seatback is pivotably connected to the seat frame or seat back at a second pivot point. As a result, the seatback becomes a lever arm upon which forces are applied. These forces, when coupled with the play within the latch mechanism causes the seatback chucking motion. This occurs even if the seat is in a locked position. This movement is exacerbated by the length of the seat and the motion, therefore, is more noticeable at the upper end of the seat. For example, the seatback may tend to oscillate when the vehicle encounters rough road conditions or travels at high speeds. In order to reduce the chucking motion, bulky or close tolerance pivot mechanisms have previously been used. However, due to the size and cost limitations, an alternate mechanism that is less costly and occupies a reduced space would be beneficial. Also, a mechanism that combines the strength and support benefits of a strong load-supporting latch with anti-chucking properties would be beneficial.
The invention relates to a seat latch assembly that includes a seat bottom that has a first frame member, a seat back that has a second frame member that is partially mounted on the first frame member about a first pivot, and a latch mechanism. The latch mechanism includes a pin mounted on one of the first and second frame members. The latch pivotally attaches to the other of the first and second frame members about a second pivot. The latch has an open angled hook portion and is movable about the second pivot between a disengaged position and an engaged position. In the disengaged position, the hook portion is spaced from the pin. In the engaged position, the hook portion is in contact with the pin to hook the pin to prevent the first frame member from pivoting relative to the second frame member about the first pivot.
The hook portion of the seat latch assembly includes a flat formed therein that defines a first line. A line is formed at an angle xcex2 that is greater that 90 degrees relative to a second line defined by a line extending through the second pivot and the flat. The angle xcex2 is preferably 95.7 degrees.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.